1. Field of the Invention
Aspects of the present invention relate to an array type inkjet printer and a method of determining the condition of nozzles in the array type inkjet printer. More particularly, aspects of the present invention relate to an array type inkjet printer which determines the condition of the nozzles using a plurality of patterns and a method of determining the condition of nozzles in the array type inkjet printer.
2. Description of the Related Art
Inkjet printers eject ink on a print medium (e.g., paper, transparency, or film) through nozzles according to a control signal. Inkjet printers are divided into shuttle type inkjet printers and array type inkjet printers according to ways that the print heads of the inkjet printers are driven.
Pluralities of nozzles in shuttle type inkjet printers are disposed in a print head in a sub-scanning direction. The head travels in a main scanning direction to print one line and travels in a sub-scanning direction to print another line. Nozzles in array type inkjet printers are disposed in the main scanning direction of the print head, print line by line in a sub-scanning direction and a print medium is moved in the sub-scanning direction.
The print head of both types of inkjet printers has a plurality of nozzles disposed thereon. If nozzles are clogged or do not operate due to a malfunction of a power supplying circuit connected to the nozzles, dead nozzles are generated. Accordingly, the image quality of the printed output degrades.
Therefore, a method of compensating for dead nozzles is required. As an example, a method of detecting and compensating for the detected dead nozzles exists. This method uses an optical sensor attached to a carriage that travels in a main scanning direction while being mounted on an ink cartridge. An inkjet printer adopting this method includes a carriage module to move the ink cartridge to a particular place at a particular speed using an encoder. The inkjet printer further includes a line movement module to move the print medium to a particular place at a particular speed.
Accordingly, the head with the plurality of nozzles disposed thereon prints particular patterns at particular places using the carriage module and the line movement module, senses the patterns by the optical sensor at the particular place, and determines if the patterns are appropriately printed through the level of the sensed patterns. The head can then, accordingly, determine if the nozzles used to print the patterns are operating normally or abnormally.
The above method of determining the condition of the nozzles using the optical sensor attached to the carriage is effective in determining the condition of the nozzles. However, if there is no carriage to which an optical sensor may be attached, this particular method cannot be applied.
The head of the array type inkjet printer may include thousands of nozzles according to a resolution or design thereof. For the purpose of convenience of explanation, it is assumed that 1200 nozzles are formed for one line. As a color inkjet printer supports four colors of cyan, magenta, yellow, and black (CMYK), the head is understood to have 4,800 (1,200×4=4,800) nozzles.
Accordingly, the above method of determining the condition of the nozzles using the optical sensor attached to the carriage cannot be used in array type inkjet printers which have no carriage and which have thousands of nozzles disposed in the print head.